The intake flow of an internal combustion engine, including fresh air and any recirculated gases, is an important parameter to control for the engine to properly achieve targeted torque and power, and to control emissions generated by the engine. The control of the intake flow is performed by many actuators, often including an exhaust gas recirculation (EGR) valve and a variable geometry turbocharger (VGT) with a position that defines the operating characteristics of the VGT. The position of the VGT can indicate a position of one or more nozzles, vanes, or other devices associated with the turbocharger.
Known controls for intake flow include targeting a specified fresh air flow and EGR flow, and controlling the EGR valve and VGT positions to achieve the both flows and therefore the desired intake flow. The EGR valve and VGT positions are each only effective at certain operating conditions, and are highly coupled with respect to effects on the intake flow parameters. Presently available controls decouple the EGR valve and VGT position through a number of techniques to achieve targeted intake flow parameters, including operating the EGR valve and VGT positions as serial controllers, and applying a mathematical transform to decouple the EGR valve and VGT position as intake flow parameter actuators.
Presently known controllers are effective for achieving the intake parameter values—for example as described in reference U.S. Pat. No. 6,408,834 entitled “System for decoupling EGR flow and turbocharger swallowing capacity/efficiency control mechanisms.” However, presently available controllers result in a system that is highly complex, that requires a great deal of effort to calibrate, and that has a coupling between the intake manifold pressure and EGR valve position and the fuel flow rate to the engine. Therefore, further technological developments are desirable in this area.